The long term objective of this research is the elucidation of the mechanisms which are responsible for the development of sperm fertilizing capacity in the mammalian epididymis. As spermatozoa pass through the epididymis, they are sequentially exposed to varying epididymal environments created by the secretion and absorption of epididymal cells. The working hypothesis is that the maturation of the sperm plasma membrane necessary for sperm-egg interaction is dependent upon the sequential interaction with hormonally controlled epididymal secretory proteins. The following procedures have been developed: 1) maintainance in vitro of epididymal explants where the interaction between all the cells of a region and their 3-dimensional structural relationship are preserved, and 2) isolation and culture of viable epithelial and peritubular epididymal cells. The specific objectives of this proposal are 1) to establish the optimal conditions for the study of protein synthesis and secretion of epididymal cells. This will be studied, after incorporation of labeled sugars and amino acids, by light and electron microscope autoradiography, SDS-PAGE electrophoresis, and immunoprecipitation; 2) to study the hormonal control of protein and glycoprotein synthesis and secretion; 3) to determine the affinity of secreted proteins and glycoprotein for epididymal spermatozoa and their effect first on sperm-egg binding and then on sperm fertilizing ability; 4) to determine the regional differences in epididymal secretion and secretion-sperm interactions; 5) to determine whether epididymal cells secrete glycosyltransferases and glycosidases which can modify the sperm surface; 6) to study epididymal secretion and secretion-sperm interaction in mutants with normal sperm production, sperm morphology, sperm motility, and low fertility; 7) to study epididymal protein synthesis and secretion during prepuberal development. Rabbits, rats, and mice will be used. These studies should provide important insights into the problem of male fertility.